Deco into the 21st century [Archive] - BSAC Scuba Diving Forums

ray

07-01-2006, 17:05

Hi.

Seeing as BSAC issues approved deco tables for training and normal air diving practises, would BSAC consider issuing an electronic version like V Planner etc, that have been approved for technical diving, being issued to cover all the different types of diving, being awarded to the divers with the Nitrox.Trimix, SCR, CCR and having the relevant certs, whether BSAC or approved cross over.

Is it now the time to sort this out, now that the practise of technical type of diving is being catered for in training, and is carried out more and more within BSAC, and will probably become the norm in club diving as time goes by.

Most of our club are at least Nitrox qualified, and are actively encouraged to dive with this gas.

Would you like the BSAC to provide this deco information even if you have to buy it?.

Answers on a post card please

Alan Ewart

07-01-2006, 17:48

Hi.

Seeing as BSAC issues free approved deco tables for training and normal air diving practises, would BSAC consider issuing an electronic version like V Planner etc, that have been approved for technical diving, being issued to cover all the different types of diving, being awarded to the divers with the Nitrox.Trimix, SCR, CCR and having the relevant certs, whether BSAC or approved cross over.

Great idea

Is it now the time to sort this out, now that the practise of technical type of diving is being catered for in training, and is carried out more and more within BSAC, and will probably become the norm in club diving as time goes by..

Totally agree

Most of our club are at least Nitrox qualified, and are actively encouraged to dive with this gas

Again yes, no-one in my branch is less than Nitrox qualified!!

Would you like the BSAC to provide this deco information even if you have to buy it?.

YES

Chris Cherrington

07-01-2006, 18:37

This leads on from all the debate on the 88s....

My view is why should BSAC re-invent the wheel? All that is needed is for an existing package to be "approved" (this is the case for RB anyway..)

A club with 40 thousand members should be able to get a good discount on a commercial package I reckon.. :)

Alternatively "approve" a number of packages (like IANTD) and leave it up to the individual to decide which is the most appropriate for the circumstances. BSAC could then introduce an SDC along the lines of the "decompression specialist" course offered by the agency in my avatar... (no connection :D)

I think BSAC Technical are close to this and are to be applauded for it.

In fact while we are on the subject and it gives me the chance to air my hobby horse why not scrap the convoluted twaddle about the 88s in FCD and introduce some deco "general knowledge" in the exam instead. I've yet to meet anyone that's SD or above that uses the 88s.....

Chris

Steve Pearson

07-01-2006, 23:19

Hi Ray

You're one step behind, BSAC no longer issue 88's free anymore..... They charge about £17 for a set.

I agree we need to move on, and an electronic version of an existing deco program should be adopted.

I think a lot of people just dive on the fly, with their computers. We probably only use tables when teaching diver grades & Nitrox.

Those of us diving trimix are probably the only group who actually cut run-time slates, and even those are prepared from an electronic deco prog.

Steve

Watch this, I'll get 90% of the people on here now telling me that they always use tables....haha :D

Steve Pearson

07-01-2006, 23:24

A very good free deco prog can be found at www.hlplanner.com

Set the safety margin % to 23%, for quite a good conservative run time, pretty much in line with pro planner.

Nice package to use, clear and easy, and will calc best gas mixes for given depths.

Anyone not too sure on how to use it, give me a shout.

I'd welcome any comments from users of other progs as to how it compares

Steve

ray

07-01-2006, 23:26

Vic

08-01-2006, 13:41

A very good free deco prog can be found at www.hlplanner.com

Another can be found at http://www.ddplan.org/

HTH

Vic.

Rick

08-01-2006, 14:05

might be an idea to add those to the links section of the forum

Adrian Kelland

08-01-2006, 14:18

might be an idea to add those to the links section of the forum
Will do Rick.

ray

08-01-2006, 14:34

Hi.

Thanks guys but I have these deco programmes.

The point I am trying to make is, BSAC should adopt a programme to use throughout the collective club structure, whether it be for training or diving, that has been agreed with any insurance that BSAC carries, cut down on as many grey areas as possible, and makes a uniform platform for deco calculations, and maybe if it is not to complicated to use a printed version of any mixed gas tables.

iainmsmith

09-01-2006, 17:50

The point I am trying to make is, BSAC should adopt a programme to use throughout the collective club structure, whether it be for training or diving, that has been agreed with any insurance that BSAC carries, cut down on as many grey areas as possible, and makes a uniform platform for deco calculations, and maybe if it is not to complicated to use a printed version of any mixed gas tables.

I have to disagree. I don't see how BSAC could sensibly dictate a set of parameters for decompressing from technical diving.

How strictly are you going to require adherence to published tables? What limits will be set? Which variables is the user "allowed" to adjust and within what range (have a look at the "Advanced" settings of V-planner for the selection available.)

Will there be a requirement that deco profiles be at least as conservative as the "official" tables? How do you judge that conservatism when people are planning their deco using different settings?

What gases would you produce tables for? What deco gases would you use for these?

What about lost gas tables? How does the organisation as a whole make a judgement on behalf of the individual diver who has to decide how to balance the risk of getting very cold due to an extended decompression profile against the risk of getting bent by surfacing after shorter interval?

IMO, if you are doing technical diving, you should understand enough deco theory to have a basic understanding of how the profile is generated (and in what areas the maths may not match reality) and to make your own decisions about a) which software to use and b) how to configure it. Given that the BSAC is still teaching the '88s, almost 20 years after they were published, what hope of keeping technical tables tables up to date as understanding of decompression theory progresses.

Additionally, given that BSAC's insurance is "Third Party Liability", following any given profile is unlikely to hurt anyone other than yourself and your buddy (who should also have known what he was getting into), hence it doesn't strike me as a particularly significant issue.

Doubtless if and when the BSAC Trimix course is published there will be some deco planning method included with it. What that will be remains to be seen. What it should not be is the one and only way in which technical dives may be planned, just as "Proplanner" has never been the only software permitted for planning Extended Range dives.

Iain

ray

09-01-2006, 18:07

I have to disagree. I don't see how BSAC could sensibly dictate a set of parameters for decompressing from technical diving.

How strictly are you going to require adherence to published tables? What limits will be set? Which variables is the user "allowed" to adjust and within what range (have a look at the "Advanced" settings of V-planner for the selection available.)

Will there be a requirement that deco profiles be at least as conservative as the "official" tables? How do you judge that conservatism when people are planning their deco using different settings?

What gases would you produce tables for? What deco gases would you use for these?

What about lost gas tables? How does the organisation as a whole make a judgement on behalf of the individual diver who has to decide how to balance the risk of getting very cold due to an extended decompression profile against the risk of getting bent by surfacing after shorter interval?

IMO, if you are doing technical diving, you should understand enough deco theory to have a basic understanding of how the profile is generated (and in what areas the maths may not match reality) and to make your own decisions about a) which software to use and b) how to configure it. Given that the BSAC is still teaching the '88s, almost 20 years after they were published, what hope of keeping technical tables tables up to date as understanding of decompression theory progresses.

Additionally, given that BSAC's insurance is "Third Party Liability", following any given profile is unlikely to hurt anyone other than yourself and your buddy (who should also have known what he was getting into), hence it doesn't strike me as a particularly significant issue.

Doubtless if and when the BSAC Trimix course is published there will be some deco planning method included with it. What that will be remains to be seen. What it should not be is the one and only way in which technical dives may be planned, just as "Proplanner" has never been the only software permitted for planning Extended Range dives.

Iain

I hand this over to the forum, I do not have the answers unlike this reply.

It seems to me you have answered your own points, as all these are skills are done with greater knowledge, and how do you get greater knowledge?.

Start at the begining.

Nigel Hewitt

09-01-2006, 18:51

ray

09-01-2006, 19:10

I would be on the side that says BSAC should not adopt a software program for planning technical diving. If you are a big enough girl or boy to plan decompression or to not plan it this should be a decision you should own. Passing the buck and saying effectively "I can't be bothered to understand the implications, I let somebody else make these decisions for me" is acceptable on shallow, no stop dives, debatable on nitrox deco dives but daft once you let helium into the equation.

You may run mathematical models on supercomputers, you may read the books, you may just discuss it with somebody you trust but it has to be your decision and you have to call when you amend it.

Thanks Nigel.

But if BSAC are running techie courses, these will be aimed at the diver new to these skills, and it seems sense to me that we all train using the same training schedule to make the training uniform, and I would have thought deco information should fall under the same umbrella.:confused:

Of course when you have become proficient in the method of diving you have chosen, you can do what ever you want as far as deco info/choice, as long as it is within BSAC mandate for your training qualifications.:)

Obviously you are very experienced in your diving choice, but at one time you new nothing, and had to start from scratch, so did you train BSAC or other agency, whoever you trained with would have had their own training schedule, and literature to learn from, all of which would have been pretty uniform throughout the whole diving organization.:rolleyes:

Steve Pearson

09-01-2006, 19:13

Nigel,

Are you a descendant of the reluctanttochangeasaurus, the dinosaur that still exists within the diving community. I think not, but always good for a stimulator of discussion. :)

Is a deco program not just a tool that works out the calculation for you. Perhaps an abacus with smb's for balls would do the job as well, but not as quick.

If you were going to work out the calculations using the formulae would you not use a calculator to make the maths easier and quicker to do. Using a deco prog is just an enhancement on that. Of course those of us who have done the courses are big enough to work it out, but why bother. We have more important things to be thinking about than sitting down and doing the maths.

I'm sure you dive with a computer and not just a depth guage, watch, and tables....why, because you trust the manufacturers and mathematicians who programmed the algorithms to have got it right. Why not trust the writers of the deco programs to have also got it right.

I don't care wether BSAC adopts a software program and no one else in reality probably does either. We'll just keep on using the ones weve got.

We live in the real world, and need to face reality.

Steve

Vic

09-01-2006, 19:29

But if BSAC are running techie courses, these will be aimed at the diver new to these skills, and it seems sense to me that we all train using the same training schedule to make the training uniform, and I would have thought deco information should fall under the same umbrella.

Why?

Selection of a deco algorithm is a very personal thing. There are a number of different types of risk to consider, and diving in this manner involves an amount of responsibility that you just cannot palm off onto somebody else. You have to take your own decisions - and they will likely be different from the decisions that I take, in the same way that my decisions are different from those taken by many other divers.

Pushing everyone into the same way would seem to me to be a very unwelcome development.

at one time you new nothing, and had to start from scratch, so did you train BSAC or other agency

I trained with IANTD.

whoever you trained with would have had their own training schedule, and literature to learn from, all of which would have been pretty uniform throughout the whole diving organization.

Some bits were uniform - but deco procedure was not. Part of the course was a discussion of how we intended to plan our dives - and there were as many views as there were people in the room. It was down to us to solve the issues that came out of that - and rightly so.

Vic.

Vic

09-01-2006, 19:32

Is a deco program not just a tool that works out the calculation for you. Perhaps an abacus with smb's for balls would do the job as well, but not as quick.

Woah, there. Slow down.

No-one's suggesting that you shouldn't use a deco programme - just that we shouldn't try to push everyone to use the same one.

I don't care wether BSAC adopts a software program and no one else in reality probably does either. We'll just keep on using the ones weve got.

So if BSAC were to suddenly endorse one particular package which you don't surrently use, you'd ignore their recommendations? I think that was kinda what Nigel was getting at...

Vic.

ray

09-01-2006, 19:44

Why?

Selection of a deco algorithm is a very personal thing. There are a number of different types of risk to consider, and diving in this manner involves an amount of responsibility that you just cannot palm off onto somebody else. You have to take your own decisions - and they will likely be different from the decisions that I take, in the same way that my decisions are different from those taken by many other divers.

So do you run your own profiles or do you use one that have all ready been invented?[/B]

Pushing everyone into the same way would seem to me to be a very unwelcome development.
[B]BSAC training is all about pushing everybody the same way.

I trained with IANTD.
No problem with your agency.

Some bits were uniform - but deco procedure was not. Part of the course was a discussion of how we intended to plan our dives - and there were as many views as there were people in the room. It was down to us to solve the issues that came out of that - and rightly so.

I am not saying your veiw on deco procedure is wrong, but what if BSAC commissioned a new deco schedule which knocked the spots of all else on the market, would you use it, or draw up your own schedule?.[/

Vic.[/QUOTE]

ray

09-01-2006, 19:52

Woah, there. Slow down.

No-one's suggesting that you shouldn't use a deco programme - just that we shouldn't try to push everyone to use the same one.

So if BSAC were to suddenly endorse one particular package which you don't surrently use, you'd ignore their recommendations? I think that was kinda what Nigel was getting at...

Vic.

Thanks.
But your comments seem to be coming from a diver who has already learned the skills, and from the lofty heights you are talking from might not be the answer to the rest of the diving world who might not be as skilled as you.

Janos

09-01-2006, 19:52

Is a deco program not just a tool that works out the calculation for you. Perhaps an abacus with smb's for balls would do the job as well, but not as quick.

If you were going to work out the calculations using the formulae would you not use a calculator to make the maths easier and quicker to do. Using a deco prog is just an enhancement on that. Of course those of us who have done the courses are big enough to work it out, but why bother. We have more important things to be thinking about than sitting down and doing the maths.

What about this one (http://www.nigelhewitt.co.uk/diving/index.html) for the iPAQ?

Anyway. I agree with Nigel. I think that the 'tech' style courses should promote a discussion of the pros and cons of the common packages and the different types of algorithm. There's an interesting thread on YD at the moment about DOTF which has side-tracked into what happens when you try and use deep stop algorthims when diving with a Suunto computer.

Janos

Vic

09-01-2006, 19:57

So do you run your own profiles or do you use one that have all ready been invented?

That depends on what you mean by "invented".

I use methods developed by a number of people, and tested by many. But I choose my own parameters, and therefore I cut tables personalised to my dive. Sometimes, those parameters are influenced by the choices made by my buddy, who may be diving a different model to the one I'm diving.

BSAC training is all about pushing everybody the same way

Absolutely disagree. BSAC is about training thinking divers, not clone automata.

I am not saying your veiw on deco procedure is wrong, but what if BSAC commissioned a new deco schedule which knocked the spots of all else on the market, would you use it, or draw up your own schedule

If BSAC commissioned a set of tables that would do for me what my current system does, and if I were suitably convinced of its safety, then yes, I'd probably use it. Unfortunately, that isn't possible; one of my principal requirements is flexibility, and that's not possible with a single fixed set of tables.

Vic.

Janos

09-01-2006, 20:00

I am not saying your veiw on deco procedure is wrong, but what if BSAC commissioned a new deco schedule which knocked the spots of all else on the market, would you use it, or draw up your own schedule?.

I think this is the problem. There is going to be no single deco programme that will knock the spots off the others. I regularly use three different algorithms to calculate my deco depending on the dive I am doing.

Also, how do you judge if a programme knocks the spots off other programmes? It's hard to devise a meaningful test.

This is why ultimately it comes down to the user. Technical [1] diving is not something that should be undertaken lightly and people should be in a position (ie they should have the understanding) to make their own choices.

To be fair, I bet that initially most people will use the software that their instructor uses, but that's not a reason to talk about other profiles.

Finally, if Vic is at a lofty height, then it would be nice for the knowledge that he has to be included somewhere in the syllabus, so we can all be at the same lofty height :)

Janos

[1] - I'm still looking for a word other that "technical"

Vic

09-01-2006, 20:03

But your comments seem to be coming from a diver who has already learned the skills

There's an answer to that - you have at your disposal all the tools I had when first I wanted to understand what I was doing to myself. In fact, there are *far* more resources available now than there were then.

the lofty heights you are talking from might not be the answer to the rest of the diving world who might not be as skilled as you.

It is my view, and one shared by a number of people here and elsewhere, that anyone conducting diving with a non-trivial amount of decompression to do owes it to himself to read up on these sorts of issues, and so be suitably informed to take the decisions we're talking about. To attempt to by-pass that learning phase by off-loading the task onto BSAC is at best foolhardy, at worst suicidal.

Vic.

ray

09-01-2006, 20:20

Thanks Vic

There's an answer to that - you have at your disposal all the tools I had when first I wanted to understand what I was doing to myself. In fact, there are *far* more resources available now than there were then.

(That is a good way to learn, read and understand as much as you can, then take the course for the skills and then you can clear up any points you do not understand.)

It is my view, and one shared by a number of people here and elsewhere, that anyone conducting diving with a non-trivial amount of decompression to do owes it to himself to read up on these sorts of issues, and so be suitably informed to take the decisions we're talking about. To attempt to by-pass that learning phase by off-loading the task onto BSAC is at best foolhardy, at worst suicidal.

(There must be quite a few suicidal divers then all trusting the BSAC training, and if that is unloading that is what the whole BSAC training schedule is already taking on board, maybe not everybody is that clever and may have to be shown how to do things all the way down the line, and it will then be in the instructors remit to fail candidates that do not show the skills .)

(I hope the new technical training will be as thorough as the training already given within the BSAC.)

Nigel Hewitt

09-01-2006, 20:36

Lots of good points but can I have another go...

I have trained on OC and then CCR with various agencies and every new course has used a different system to generate stops. Nobody said theirs was the best or the only system but that it was good and that the instructors themselves used it. This is good. I would be very happy to see those coming up the BSAC ladder to get that breadth of options placed before them. A tech course is not OD. It is not I-do-you-copy. It must be you-understand-you-think.

I like deep stops, I don't like get-you-out-quick systems, I like conservatism, I don't like it forced on me.

My current (current is the key word as I'm still learning) system is to carry tables and a depth timer plus a computer all set for zero conservatism. I like zero conservatism so I have something planning the quickest route back to the surface and I accept that that would be a risk. Then I add slow ascents, possibly deep stops although my current VR3 does them now, and lengthened shallow stops so the conservatism comes from my head. On the evil day that my buddy looses the plot I am equipped with real numbers to decide the plan. Am I missing 10 minutes of stops or 30 minutes if I surface him now? Adding time is easy. Be a coward - good move - but if you are getting cold maybe don't do the extra 15, make it just 10.

Now you can't teach somebody that. You plan a schedule the whole group of trainees can do and then watch them hit the run times. I am deliberately not hitting run times. It's a system that works well on the CCR as I only have to do gas planning for my bail out. Admittedly I did use it on OC as deep stops didn't cost me much gas and I could have stretched the shallow stops until the SPG complained although it never did.

I don't think hitting one program every time, even if it is mine, is a good idea. I still use my own software to plan the dive and then dive the computer with the DDplan tables as back-up. We had a discussion on FCD recently and FCD was described as a thinking qualification where the 'student' does much of their own research. Tech diving needs to be much like that. The questions are not whether you can remember chapter and verse from the manual but can you make safe decisions when planning the dive and safe decisions when executing it. Your deco plan is crucial to all of this and everybody admits is it more art than science at times.

Personally I always remember the old joke that you can tell the real expert in the crowd: he's the guy that says it will take the longest and cost the most. I tend to feel like that about deco software. I have a feeling that the one that says keeps you the longest in the water could well be the one with my best interests at heart.

Sorry it's so long.

Gareth

09-01-2006, 21:03

Hi all

Most of what I would have said has been said before by all parties. But a couple of points.

Nice idea about uniformed deco planing tools but in my opinion not practical on a number of fronts.

We already have 'discusions' about the max PO2 that we should be using, this is based on valid individual views. Imagine the 'discussions' we will have if the BSAC say's use table X!

Imagine the fun of justifying your dive profile using your preferred algorithm to a DO who reads the BSAC paper work but doesn't understand that your table is as valid as the one the bsac recommended! (His usual dive is 20 minutes at 20m & thats agressive!) Then there is those lovely legal people! Imagine the fun they would have if you didn't use the recommended software.

I know the ERD coarse comes in for a lot of stick on this form, but if you look at the way it is structured, it is not a lecture, its a discussion, debate between the instructor & the students & between the students.

Its about understanding risk, & accepting the degree of risk YOU are happy with. This is what Technical (I hate that discription) diving is!

On the last coarse I ran, the students used a software to plan their assessment dive that was considerably more agressive than mine! They didn't realise that I would half the bottom time & then use the same profile (after all this is an assessment not a real dive - & I don't want bent students if something goes wrong)!

One final point. If the BSAC was to adopt table / software (decompression theory) X. Then there was a change in thinking about how to safely decompress, how long would it take for the BSAC to change!

(My keyboard is stuck using !!!!!!!)

Cheers all

Gareth

Paul Oliver

09-01-2006, 22:02

Yes, i have to agree with Gareth on this, i thoroughly enjoyed the ERD course and the style of delivery with the discussion type approach. We looked at 3 deco package options (IIRC) and i now flit between several. Not sure i have the right one for me yet.

I have an approach like Nigel though, i want to know when its time for me to get out, then add a bit as i see fit, so if it goes wrong i have an accurate idea of what i am cutting out etc.

I personally feel the ERD course and its value is lost to a degree due to lack of publicity and easy access to instructors. In the end i traveled the width of the country (Southern end) to do mine, but have used it an enormous amount since then.

However BSAC Recommending a few software packages would not go amiss i think.

iainmsmith

09-01-2006, 22:03

I hand this over to the forum, I do not have the answers unlike this reply.

Sorry if I gave that impression - I rather thought I was simply posing a number of questions!

It seems to me you have answered your own points, as all these are skills are done with greater knowledge, and how do you get greater knowledge?.

Start at the begining.

Indeed. For what it's worth my "technical journey" could have been said to start with my BSAC ANX course in 1999. I spent the next couple of years reading widely and playing with various bits of software to try to understand what they were telling me. I then progressed to actually diving some of the profiles (which were generally rather more conservative than the BSAC nitrox tables). As I became more experienced, I started adjusting the degree of conservatism, based on my reading of what others were doing. Then I did my trimix course and learned more about interpreting the computer-generated profiles. And I continued reading...and adjusting...and reading some more.

My objection to a set of "issued" tables is not that they would provide a safe starting point for most trimix dives - it's that to do so, they would have to be what many people would consider unnecessarily conservative. Given that current BSAC decompression recommendations are that any profile dived should be at least as conservative as the '88s, the potential for some to interpret these "official" tables in the same light concerns me. I also agree with the sentiments expressed by others that technical diving is about making ones own decisions (not that everyone will necessarily agree with them!), not blindly following what is dictated.

Iain

ray

10-01-2006, 12:19

Hi guys,
Some very good posts still posted from a knowledgeable slant on things though.

Would anybody who has not done the training yet, like to comment on what they would expect within the BSAC course, maybe would they expect BSAC to provide along with the deco training, BSAC deco products to enable safe deco.

Of course you guys involved with the new training might have already sorted all this out, would you like to comment on any of the point's raised in the posts?.

Chris Cherrington

10-01-2006, 15:13

However BSAC Recommending a few software packages would not go amiss i think.

FWIW I recon that having a standard package would be a good idea for training purposes.

When introducing students to the ideas behind accelerated deco and gas switching most educators would want to run some examples and at this point if everyone has a copy of the software (or tables generated by it) you can do what-if scenarios and the like.

However, I concur with the view that what you use for real is a personal choice.

As mentioned there are couple of free ones. Gordon's DD Planner is one I use as it generated tables, but for diving I use V Planner, which (as you all know) does not..

(Free life membership for me old mate Gordon as a thank you?)

Chris

iain aitchison

11-01-2006, 22:27

Hi All,

could you imagine that at some point BSAC decides not to issue a table and only teaches how to get the best from the electronic versions - dive computers, dive tables on laptop programmes etc. i.e. no hard copy stuff at all?

comments please

(It would be a lot more sense than asking about BSAC tables to test deco knowledge at FCD).

That would mean BSAC could focus earlier and in more detail on how best to use the computers and how for higher skill levels deco can be tuned to teach the different advanced techniques including designing conservatism, choosing models, deep stops, etc. and of course for gases and gas choice. We can do it, and many of us have moved or are moving onto doing it, so why not teach it? Air and Nitox are mainstream and as soon as CCR goes mainstream Trimix or Heliox will go too. Then the game changes again.

I am on a VR3 myself, turned up quite high. The thing is only a pain at altitude where on a shallow dive it needs a manual start. I do tend to do a print off to a slate for 3 dive plans on a tech dive and do the deep stops off the computer and the full oxygen hang off the most appropriate table on the slate - if that makes sense. That way the oxygen hang is not shorter on the computer and if it goes down I am somewhere near a run time on the slate.

I have a feeling we will look back on what we do now and think - how did I survive doing my deco like that back then. :eek:

iain aitchison

11-01-2006, 22:30

Gareth

11-01-2006, 23:33

Ian

I look back on some dives now & wonder how I got away with it.

In 96 I did the Skalla

49m 30min
9m 4min
6m 7min
3m 25min

This was valid profile on the computer!
This was after a solid weeks diving, all on air!

The Autumn of 96 I did my advanced Nitrox coarse - after that my decompression got a lot more conservative!

Gareth

PeteM

12-01-2006, 10:03

could you imagine that at some point BSAC decides not to issue a table and only teaches how to get the best from the electronic versions - dive computers, dive tables on laptop programmes etc. i.e. no hard copy stuff at all?

comments please

I don't like the idea. Remember we need to cover a new Ocean Diver's training as well. Not everyone has a PC and not everyone is computer literate enough to use a deco program and at the level I am talking about is not able to do a mental reality check on the figures (OK the Marshall can do it for them). By mandating (e.g.) Proplanner we are putting big barriers in the way of new divers.

So for this level we are in effect saying use a dive computer. No problem with that from a dive perspective but I have one from a teaching dive planning POV. One of the good things about a deco table is you can get someone to plan the dive for both a deco and gas management. This is I think vital, we see far too many people dropping into the jump in and swim around until we get to 5 minutes deco/80bar school of dive planning. By taking away the ease of use of a pre printed table we will encourage this attitude earlier. My branch makes a point of getting inexperienced divers to plan a bailout option on tables even if diving a computer and I get the impression this is common. Without preprinted tables of some time this will not get done - who realistically is going to take a notebook/PDA for general use on a 20m bimble? The only practical alternative to make sure the planning happens is a set of tables built by the DO, so we are back to preprinted tables but with no standard format across the whole club.

To be honest I think when we discuss this sort of thing we often loose sight of the fact the main use of the 88's these days is for inexperienced divers. Once you get to a reasonable level you will either by using a dive computer and gas planning from experience or you will have taken the techincal route and preplanned stuff before leaving home.

MattS

12-01-2006, 15:19

could you imagine that at some point BSAC decides not to issue a table and only teaches how to get the best from the electronic versions - dive computers, dive tables on laptop programmes etc. i.e. no hard copy stuff at all?Briefly. The use of tables helps to develop a feel for decompression that I doubt you could accquire so easily by using software. Perhaps we need to consider the lessons from general education where over reliance on calculators has bred a generation that can not relate the sum to the answer.

Personally I think the current problem is that BSACs decompression teaching is not exactly 'joined up' By that I mean the tables we currently teach bare no resemblance to the computer and desktop generated profiles most of us dive. Nowhere is this more apparent than at ERD where the accelerated 80% profiles being taught are often longer than the corresponding air profiles on the 88s.

It is possible to use tables which produce profiles roughly similar to the majority of computers, because the majority of computers are based on the same algorithm. I suspect that those of us that did our Nitrox training outside of BSAC are already familiar with applying EAD to Buhlmann tables for planning and bailout purposes.

From the assumption that all modern tables (including the 88s) have an acceptable bends incidence, I propose that teaching decompression planning methods which result in consistant and logical results will help divers at all levels to better understand the actual risks. It's not the concept of manual calculation which causes the confusion but the flavour of calculation that we happen to be teaching. In other words we may be in danger of throwing the baby out with the bathwater.

Going a stage further, safe decompression is a holistic strategy rather than a tactical solution. It is very easy to get bogged down in the minutia of tables and ignore such things as hydration and diet which are (probably) just as important. The length of stops is only one aspect, and despite the common misunderstanding that longer = safer it really is not that simple. It would perhaps be appropriate for BSAC to first state a recommended strategy that should be promoted before turning their attention to finding a planning method for it. For instance I personally stick to a 10m/min ascent rate, safety stops, deep stops and a final stop closer to 3m than 6m. I know exactly why I do these things and I would like to think they reflect modern mainstream good practise. However this is markedly different from decompression according to the 88s and the question is whether I should be encouraging those that know less to follow my example?

So I could agree with the idea of a BSAC decompression application just as long as it is part of an overall consistent strategy....and noone starts claiming it is the only valid solution.

Nigel Hewitt

12-01-2006, 16:15

I don't like the idea. Remember we need to cover a new Ocean Diver's training as well.Hang on. We started talking about tech diving. Nobody says we should take the easy to use '88s out of OD hands. The whole question was should there be a BSAC recommended tech diving decompression planner and I argued 'no', just like there isn't a BSAC recommended BCD or a regulator.

I don't expect everybody to research decompression theory, Tauchmedizin is on my bookshelf but then I'm a geek, but I do expect them to know enough to make a call as to what system they use, how conservative they want to be and when to up it and when to relax it.

PeteM

12-01-2006, 16:44

Hang on. We started talking about tech diving. Nobody says we should take the easy to use '88s out of OD hands. The whole question was should there be a BSAC recommended tech diving decompression planner and I argued 'no', just like there isn't a BSAC recommended BCD or a regulator.

We may have started talking about that but the question to which I responded (and quoted) was talking about a complete move away from printed tables to just using planning software and dive computers.

For what it is worth I agree with you.

Nigel Hewitt

12-01-2006, 17:05

We may have started talking about that but the question to which I responded (and quoted) was talking about a complete move away from printed tables to just using planning software and dive computers.

For what it is worth I agree with you.I wasn't actually aiming at you but using your quote to whinge about a thread that was asking a good question drifting off into the realms of silly.

Mia culpa. I should have been clearer.

Colin Marriott

13-01-2006, 09:44

I think the problem here would be that if two divers turn up to do a deco dive with deco schedules cut from different deco planning packages.

If one package puts the emphasis on deep stops, and the other doesn't, then the two divers are going to have different stop schedules.

Do both divers do both schedules, waiting for one-another ( you know the answer to that already )?

How would these 'unforeseen' stops affect gas planning?

Whatever gets used, it must have some commonality about it.

ColinM

Nigel Hewitt

13-01-2006, 10:11

I think the problem here would be that if two divers turn up to do a deco dive with deco schedules cut from different deco planning packages.Well I've hit it with different computers where we just dive the next stop on either wrist.

eg: I will signal *deco* *24* and my buddy signals back *deco* *33* so we head on up to 33 and maybe my 24 will clear and we will leave it for an agreed 18. One of the nice things about the rebreather is that gas planning becomes bailout planning and I know my two 7L stages (bottom mix and 50%) will get me out of dives I wouldn't tackle so between us we have masses of gas even if one of us has a terminal loop fault. If we were cutting a slate we'd either do it together or decide which one to use before we got in the water.

I would say that coming with different plans is actually a good thing. If one demands more stops I'm happy to go with it unless it because somebody stuffed in daft conservatism factors. There are times when staying in the water a lot longer increases the total dive risk rather than decreases it. I prefer the conservatism to come from my head so it is adjustable. In fact a lot comes from boosting the loop oxygen above that which the computer knows about at 6m - provided the CNS number is not bad.

iain aitchison

16-01-2006, 22:24

I think a lot of people just dive on the fly, with their computers. We probably only use tables when teaching diver grades & Nitrox.

Hi Steve,

This is why I was making the point below. Why do we as BSAC teach something "when teaching diver grades" and then actually later move into all sorts of other ways of doing it which we do not teach?

It might be radical to stop teaching paper tables, but no longer completely unrealistic.

I think too that a lot of divers wing their dives, even sometimes their deco dives on the basis of their computers and weigh up during the dive depending on gas and deco what to do next.

regards
Iain

ray

16-01-2006, 23:02

Hi.

Unless I have missed it, there has been no official response from anybody from the BSAC training, to any of the questions raised.

Would be nice:rolleyes:

Steve Pearson

17-01-2006, 01:03

Hi Steve,

This is why I was making the point below. Why do we as BSAC teach something "when teaching diver grades" and then actually later move into all sorts of other ways of doing it which we do not teach?

It might be radical to stop teaching paper tables, but no longer completely unrealistic.

I think too that a lot of divers wing their dives, even sometimes their deco dives on the basis of their computers and weigh up during the dive depending on gas and deco what to do next.

regards
Iain

Hi Iain

You're completely right. We live in the real world, hence the reason that when I am teaching using tables I also show my students the deco software I personally use to cut tables/run time slates and how it works.

I admit that when I'm doing dives except for trimix, that I tend to dive on the fly, gas consumptions can vary a little depending on conditions, max depths may vary depending upon the dive, a wreck/dive might be Xmetres to the seabed/bottom, but I may only spend a small amount of time at that depth, so why penalise myself to stick to a table and come up with bags of reserve when I can get extra time on the dive whilst continually monitoring my contents and deco requirements.

I bet that most people if they're honest about it dive like this, and don't actually use tables, except for as a rough guide when in the planning stage as to the minimum time they're likely to get at that depth on the dive, and gas requirements based upon that depth and time.

I think that the gas available ends up being the deciding factor hence the reason for not sticking rigidly to tables. I always wear a back-up computer. I would also rely on my buddies computer/back-up if both of mine happened to go faulty. Worst case scenario I suppose would be to send up a blob/go up the shot and spend as much time at 6m, doing 1min stops every 3m from 27m as my gas would allow leaving a little in reserve for surfacing and buoyancy.

It's purely my choice, but I can say that i wouldn't use 88's except for teaching. Pointless with the technology available today with computers and deco software.

Steve

Chris Cherrington

17-01-2006, 11:47

It's purely my choice, but I can say that i wouldn't use 88's except for teaching. Pointless with the technology available today with computers and deco software.

Its not just BSAC that hang on to tables though (and yes my diving is just the same as you Steve). PADI for instance still teach the wheel (has it ever been used in real life?). IANTD have a whole range of tables for trimix &/or accelerated deco.

With PADI its just that they want to sell their products - that we all know, but BSAC is not a profit making organisation so it should be leading the way.

Perhaps the debate about AD is pertinent and that this is the point that deco software and theory should be taught?

I'm still looking forward to the trimix course and the shake up this will provide. Its time to think about a whole new way of training. I hope that the cheeses at HQ will seize the opportunity...

Chris

Gordon

18-01-2006, 10:30

From where I see it, the problem is deciding what are 'good' tables/programmes.
How do you no that its a naff table until you get bent?

Steve Pearson

18-01-2006, 11:21

As far as programs are concerned, I use one, and have compared the run times/deco requirements against several other popular well used programs.

There is very little difference between them as to results therefore I'm happy to use the one I do.

Steve

Chris Cherrington

18-01-2006, 12:27

From where I see it, the problem is deciding what are 'good' tables/programmes.
How do you no that its a naff table until you get bent?

That's a good point.

The basis of most tables or programs is the Buhlmann algorithms in some form or another. Typically this has been modified by the designer to his or her personal ideas or by several modifications. Some accepted modifications would include the work done by Baker for example.

Anything "new" is untried so we divers generally look at the stop times etc and compare with the table or program of our personal choice. Then we argue endlessly about why the two give different results and which is right......

Some tables or programs are doppler tested and in theory they should be safe as a result. But you'll still find plenty of argument about those both here on the "new" BSAC forum and elsewhere.

So the answer is... err... dunno :confused:

Chris

Alwassia

18-01-2006, 14:55

From where I see it, the problem is deciding what are 'good' tables/programmes.
How do you no that its a naff table until you get bent?

That is the situation i was and to some point still am in, after doing my DSAT TECDeep Diver. The instructore shows you what he uses and 2 other options which he does not recommened. So now you go on the net and try to find out more - ask 100 people and got 200 opinions. Reading the papers on the different "research" and there sales pitch did not really help a lot.

I did contact BSAC and got the reply that the program used during the ERD course maybe could posibly have the staus of someing getting close to being endorsed by BSAC, at least that is what i understood from the reply. No hit intended to the person answering me - i am greatful for the reply i got.

So now i use three programs and then stay somewhere in the middle but am not sure if that is good, right, safe or just stupid, well i got not bent till now so it could be some kind of safe.

Khaled

MattS

18-01-2006, 17:41

This is why I was making the point below. Why do we as BSAC teach something "when teaching diver grades" and then actually later move into all sorts of other ways of doing it which we do not teach?In an area where the experts can not agree it is unlikely that we will find a singe decompression method that all BSAC divers will happily agree to use. The 88s get a lot of criticism perhaps some is deservered but a lot isn't. They are still an easy to use and generally safe table. The big issue is the relevance the 88s have to modern day diving. They do not fit easily with modern dive practises and the other planning and monitoring tools which are commonly used.

It might be radical to stop teaching paper tables, but no longer completely unrealistic.Apart from the point I made in my earlier post about relating the solution to the problem. Boat electronics are a bit more reliable than dive electronics. The authorative maritime agencies are very clear that electronics should not replace good navigation skills. Despite the good advice, I am sure many day sailors put to sea without so much as a decent chart and compass. Is there perhaps a parallel with abandoning tables during teaching. The APD Vision thread would seem a case in point. The problem is reported as only affecting the display, but unless you had built up a feel for what the decompression should look like, how would you know?

I think too that a lot of divers wing their dives, even sometimes their deco dives on the basis of their computers and weigh up during the dive depending on gas and deco what to do next.As far as methodology is concerned I don't really do things any differently these days, I still plan the dive and dive the plan. What has changed are the gasses, ascent rates, and stop schedules.

Personally, with all my techie qualifications, I think it is just as daft today to jump into a non-life supporting environment without a clear idea of how long you will be there, as it was in 95 as a Novice. Whether people do it or not BSAC should not condone it IMVHO. I suspect BSAC would get a lot of criticism from UK charter operators should the training encourage people to wing it. Unfortunately the 88 tables that we currentlly teach are next to useless when it comes to planning alongside a modern dive computer or desktop app.

To summarise I don't think BSAC should stop teaching tables. I do think they should perhaps stop teaching 88s.

Chris Cherrington

19-01-2006, 13:09

..... Unfortunately the 88 tables that we currentlly teach are next to useless when it comes to planning alongside a modern dive computer or desktop app.

To summarise I don't think BSAC should stop teaching tables. I do think they should perhaps stop teaching 88s.

Matt, while I agree with you 110% I wonder what are the logistics of this? Firstly all the instructors would need to retrain with the alternative tables or PC software. Just imagine the arguments this would cause. With a commercial organisation like PADEE its easy just require it and everyone has to do it, like it or not. But with voluntary teachers.....

Second all the exams would need to be rewritten. A new series of "advanced" questions for AD, FCD and the like (maybe use the 88s to SD as a compromise). Now for myself I think very much that FCD should be deco general knowledge not the current 88 based twaddle about driving over hills and meeting up with a mate with different dive profiles in the last few hours....

I remember reading on the old BSAC forum about a TIE question (Khaled IIRC) about the difference between the RDP and the 88s. It was the usual argument but I remember at least 1 NQI admitting "no knowlege" of the RDP with the view IIRC that why should s/he know "another agency's table" (fair enough within that context I hasten to add).

The point I'm trying to make (perhaps not too well) therefore is the training implications for all the instructors and instructor trainers....

What do you folks think?

Chris

Vic

19-01-2006, 13:22

I wonder what are the logistics of this? Firstly all the instructors would need to retrain with the alternative tables or PC software.

Indeed. A simple "switch" from BSAC'88 tables to $DECO_PROG_OF_THE_DAY would involve an enormous upheaval, and I daresay more meetings and email reflectors than yer average idea. I suspect that any move we make in this direction will need to be phased; "evolution not revolution" as the nasty, cheesy, marketing-BS has it...

Second all the exams would need to be rewritten. A new series of "advanced" questions for AD, FCD and the like (maybe use the 88s to SD as a compromise).

Yep. If that's the way it's done. But here's an alternative: why don't we do this as an SDC? Keep all the deco training as it currently is for "mainstream" stuff, and *add* knowledge for those that are interested.

Now for myself I think very much that FCD should be deco general knowledge not the current 88 based twaddle about driving over hills and meeting up with a mate with different dive profiles in the last few hours....

I disagree with you here; whether or not you like the BSAC'88 model, the mechanics of planning an entire trip (including the drive home up the hill out of Portland) are important. Perhaps there are a better set of numbers somewhere than are given by the '88s, but that's immaterial - it's the planning process that is vital.

I remember reading on the old BSAC forum about a TIE question (Khaled IIRC) about the difference between the RDP and the 88s. It was the usual argument but I remember at least 1 NQI admitting "no knowlege" of the RDP with the view IIRC that why should s/he know "another agency's table" (fair enough within that context I hasten to add).

Fair enough. I see no reason why any of us should be *forced* to learn another agency's tables - but at the same time, I see such knowledge as being valuable periphery, so I'd encourage everyone to find out. It's not like it's especially difficult...

The point I'm trying to make (perhaps not too well) therefore is the training implications for all the instructors and instructor trainers....

What do you folks think?

I think we should enhance what we've got, not replace it. Not yet, at any rate.

Vic.

Chris Cherrington

19-01-2006, 16:11

Vic I like the idea of a deco SDC. Along the lines of the TDI Deco Proceedures sounds like a jolly good idea!! How hard would it be to get this taken up as a real idea?

Now for myself I think very much that FCD should be deco general knowledge not the current 88 based twaddle about driving over hills and meeting up with a mate with different dive profiles in the last few hours....

I disagree with you here; whether or not you like the BSAC'88 model, the mechanics of planning an entire trip (including the drive home up the hill out of Portland) are important. Perhaps there are a better set of numbers somewhere than are given by the '88s, but that's immaterial - it's the planning process that is vital.

I would agree that planning is vital and that any diver worth their salt should realise that ascending to "altitude" after diving carries a risk. However, after a couple of dives on your trusty Suunto how do you calculate the risk of an ascent to 300m after an SI of 2hr? Unless you have actually made the dives on the 88s the calcualtion is rubbish. Further if you use max depth and BT it is possible that you are already "bent" since the tables cannot give off gassing credit for multilevel dives.

Chris

(The more astute of you may have noticed the only bit of the example FCD exam paper that I was struggling with :D )

PeteM

19-01-2006, 16:19

I would agree that planning is vital and that any diver worth their salt should realise that ascending to "altitude" after diving carries a risk. However, after a couple of dives on your trusty Suunto how do you calculate the risk of an ascent to 300m after an SI of 2hr? Unless you have actually made the dives on the 88s the calcualtion is rubbish. Further if you use max depth and BT it is possible that you are already "bent" since the tables cannot give off gassing credit for multilevel dives.

Surely when you surface after any dive you can count yourself as a G which represents just under saturation and then use the transfer tables as a guide?

Chris Cherrington

19-01-2006, 16:31

Surely when you surface after any dive you can count yourself as a G which represents just under saturation and then use the transfer tables as a guide?

I am not familiar enough with the "rules" on the 88s to say if this is so. It seems a logical position to take IMHO.

Another technique that can be used but is not "authorised" is to use standard altitude corrections to any set of tables, or change the altitude settings on the computer so that the deco penalty is such that you should be able to surface to the altitude that you will achieve. In other words if following the dive you will ascend to 1000m you make the required stops or shorten the no stop time as if the dive took place at 1000m. Most computers do not require any adjustment below this level however. Some (for example the old Oceanics) sense atmospheric pressure when activated and adjust accordingly. Furthermore others (for example the Apeks Quantum) monitors the pressure even while "switched off" and therfore will penalise you if you have been at "altitude" prior to diving or have driven up to altitude before the dive (the Apeks manual states that you may even see nitrogen loading before immersion..)

The 88s use atmospheric pressure and the little graph shows the nitrogen that is on or off gasses according to changes in atmospheric. Taking G group sounds like a good rule of thumb but is it within the BSAC SDP ???

Chris

garethwebber

23-01-2006, 13:30

Intrigued: What was the question about the differences between tables?

Gareth

Chris Cherrington

23-01-2006, 15:52

Intrigued: What was the question about the differences between tables?

Gareth

IIRC it was just a general question. The sort the examiners like to throw in to see how you cope with a question from the floor.

Again IIRC the answer looked for was along the line that the RDP is a no stop planner to 40m and the 88s are deco tables to 50m and the different methodologies of getting repet info (RDP uses RNT and 88s a series of tables).

It wasn't meant to be hard or a "trick".

All the sad deco anoraks (that's me then :() posted about tissue groups and perfusion and the like as if you average OWI (or OWSI) should know that sort of stuff or like the student would understand it.........

When it comes to deco theory a lot of folks like to debate about things that don't really have that much impact in the real world of recreational dives with a Suunto strapped to your arm. (Oh dear me again :()

Chris

garethwebber

24-01-2006, 10:28

Thanks.

As a PADI cross over myself, the differences leave my log book amusing. First 30 dives I exit with what looks for BSAC divers, impossible codes (H onwards)!

G

Vic

24-01-2006, 14:30

As a PADI cross over myself, the differences leave my log book amusing. First 30 dives I exit with what looks for BSAC divers, impossible codes (H onwards)!

Are you sure you're defining "dive time" properly? That's the mistake I usually see when comparing RDP to '88s...

Vic.

garethwebber

24-01-2006, 14:54

PADI use dive letters through A to Q (i think - don't have my RDP here) as opposed to A to G for BSAC. They just sub-divide the grades more.

aquayle

17-02-2006, 15:29

Yes - but PADI *don't* do deco! The tables are based on no decompression diving.
I am looking at going to Stoney puddle, if I do a 36m dive for 22 mins (on air),
I can't do it under PADI RDP tables.
BSAC 88 tables give me a 1min stop @ 6m
v-planner gives me 2@15, 2@12,4@9,6@6 & 11 @3
GAP gives 1@18,1@15,1@12,3@9,5@6 &8@3

and so on....

so if I followed BSAC tables ... more onboard N2. The other software is much newer, but which one?
All in all, obviously I would choose the most conservative. Serves to make the point I guess, make your own mind up, but in this case good job (IMO) that I don't follow the '88 tables.

Andy

ray

24-02-2006, 20:24

Hi Brilliant post's from everybody, but still no "Official" response from the technical trainers/organisers on the original question:)

David_de_Marneffe

25-02-2006, 03:18

Hi guys. New to this thread, but just before I read it I sent the following email to HQ (technical issues). If I get a reply from them, I will post it. The whole point, I think, is that experienced divers are aware of all this and can make informed descisions. The average BSAC Sport Diver does not have a clue (unless the local club instructors decided by themselves to teach them proper deco theory), and does not question the '88 tables or his pure Buhlmann computer before he does an ERD or tekkie course. Here is the email:

Hi,

I am a member of BSAC 406 (Sharjah, United Arab Emirates). I am (almost) a Dive Leader, I am assistant instructor.

The following summarizes my concerns about the way decompression diving is currently taught within BSAC. If a debate on this is already open at a higher level, please pardon my impertinence. If not, I think it should be opened.

Since when I started diving, I have been interested in decompression theory and have followed the development of the VPM/RGBM algorithms vs the "classic" neo-Haldane models (Buhlmann, etc). Also, I have recently followed the IANTD Advanced Recreational Trimix course with the excellent team at Tech Asia in the Philippines.

I have come to think that the way deco theory is taught within BSAC, as well as the BSAC tables are now out of date. Indeed, there is strong evidence (both theoretical and experimental) that the neo-Haldane models overlook important parts of the physical and physiological phenomenons that occur during a dive. The most obvious experimental evidence is the number of divers affected with pains, aches and tiredness for many hours after diving, despite the fact that they dive "perfectly" according to the tables or their computers, including safety stops. This is not even mentioning the few who develop DCI despite their "flawless" dive profiles. I speak of personal experience when I say that diving VPM/RGBM profiles or even including Pyle stops resolves the problem.

Of course, I realise that this is an issue for recreational diving because of the much larger deco requirements of VPM/RGBM. Indeed, at the Sport Diver level, it is difficult to ask divers to carry deco gas and start doing gas switches and explain that deco should be almost as long as the dive itself.

However, consider the following example: a 30 minutes dive (surface to first deco stop) at 30m, according to the BSAC tables, calls for a 3 minutes deco stop at 6m. According to VPM-B, if the last stop is at 6m, deco on air, conservatism +2 (average diver) we get:
1min at 12m
4mins at 9m
22mins(!!) at 6m (total deco: 27mins)

If the last stop is at 3m:
1min at 12m
3mins at 9m
6mins at 6m
10mins at 3m (total deco: 20mins)

Looking at this and knowing that VPM-B is the latest and most likely most accurate decompression model, don't you think that the BSAC 3mins at 6m are grossly underestimated?

In view of the above, may I kindly suggest the following:

- I think the very least we owe to our members is to make them aware of these facts so that they can make an informed decision about what they want to do. This would involve:
1) At the basic level, modify the contents of the Sport Diver / Dive Leader trainings regarding decompression theory
2) Offer an "Advanced Decompression Theory" course as a skill development course, available well before Extended Range Diving, and induce divers who want to practice deco diving to follow it. It could even be made mandatory.

- Reevaluate within which limits decompression diving should be made available at the Sport Diver level.

- Induce divers who practice decompression diving to follow a nitrox course and suggest that they carry deco gas in order to reduce deco requirements.

- Review the safety stops policy.

- Review the BSAC tables.

There you go. I hope I wasn't out of place by suggesting this. But personally, knowing what I know, I definitely won't dive anymore the way I did when I just qualified as a Sport Diver.

Best regards,
David de Marneffe